Force feed lubricator



Oct. 4, 1932. w DROTT 1,880,902

FORGE FEED LUBRICATOR Filed sept. 14. 192e 5 sheds-sheet 1 Oct. 4, 1932. w DROTT 1,880,902

FORCE FEED LUBRI CATOR a; izzjyw L. w. DROTT FORCE FEED LUBRICATOR y Oct. 4, 1932.

5 Sheets-Sheet 3 Filed Sept. 14, 1926 Oct. 4, 1932 W DROTT FORCE FEED LUBRI CATOR Filed' sept. 14, 192e 5 Sheets-Sheet 4 Oct. 4, 1932. w. DRoTT FORCE FEED LUBRICATOR Filed Sept. 14. 1926 5 Sheets-Sheet 5 u j2me?? loz'o Zz Patented ct. 4, i932 LOUIS W. DROTT, OF DETROIT, MICHIGAN, ASSIGNOR T ICC01 tD RADIATOR 19t` MFG. CO., OF DETROIT, MICHIGAN, A CORPOBATIN 0F MAINE FORCE FEED LUBRICATOR Application filed September 14, 1926. Serial No. 135,352.

ward stroke thereof so that the amounts of4 oil delivered from the unit will be exactly the same as the amount passed through the sight feed on each inward stroke of the primary pump, thus making the unit accurate and Y efficient in its operation.

Another object of my invention is to connect the stroke shaftof theunit with its operating cam by a yoke which is open at one Y end so that the yoke may be slid endwise on and o of its cam and be placed in and removed from the reservoir with-out dismann tling either the cam or its shaft or stopping the rotation thereof or interfering with or4 removing any of the other pump units if the lubrica-tor is of the multiple unit type.

A further object of my invention is to locate the ball checks of the unit remote from the primary and delivery plungers so that the balls can not follow the plungers on their outward strokes and thus fail to seat at the 3'0 proper time on the inward strokes of, said plungers to make an inaccurate lubricator.

A still further object of my invention is Vto provide the lower side ofthe unit against oil D A leakage so that the oil under excess pressures, g" as caused by clogging up of the delivery line7 will be caused to lea-k through the packings of the plungers to the outside of the unit and visibly indicate the fault-y condition of the line so that it may be quickly attended to.

Another object of my invention is to-locate the check valve for the suction tube of caf the unit at the extreme lower end of said tube, so as to be as close as possible to the bottoni wall of the reservoir and thus insure im- 5 mediate starting of oil suction in the 'operanr tion of the pump.

A further object of my invention is to pro-v low the later to operate at full stroke at all times for full oil delivery while the stroke of the suction plunger may bey adjusted to regulate the amount of oil which may be delivered by the delivery plunger.

A further object ofmy invention is to provide a structure whichmay be easily and readily assembled and dismantled without theV use of skilled labor or specialinstruction. f

, The invention consists further in the mat`-- ters hereinafter described and claimed.

In the accompanying drawings- Fig. 1 is a front view of a force bricator embodying the features of my invention;

Fig. 2 is an end View of the same;

Fig. 8 is an enlarged vertical sectional view through a pump unit onA line 3-3`of Figs. l and l4c; f

Fig. t is an enlarged fragmentary top plan view of theV lubricator Vwith one unit re-v moved to show the slot therefor in the cover plate of the reservoir; y

Fig. 5 is a longitudinal vertical view taken on line 5--5 of Fig. l; f

Fig. 6 is an enlarged vertical sectionalv view taken through one end of the cam shaft on line 6 6 of Fig. 2;

Fig. 7' is a similar sectional view through the ratchet drive at the opposite-end of said shaft; 'Y

Fig. 8 is a front View of the ratchet drive taken on line 8 8 of'Fig. 7

Fig. 9 is a top plan view of the end of the cam shaft at the ratchet drive; Y

Figs. 10- and ll show the manner in which a. pump unit is removed from its stroke shaft and how the latter is removed from the reservoir;V f

Fig. 12 is aside view of to that shown in Fig. 10;

Fig. 13 is an enlarged sectional plan View taken on line 13-'13 of Fig. 10;

Fig. 14 isan enlarged plan view of the the unit, opposite v unit at the seat for the sight feed glass; and

Fig. 15 is a view showing Vhow the cams may be set about the cam shaft for operating the pump units in alternation.

As shown in the drawings, he lubricator feed lu- 'Y10 and the reservoir to secureY the vthe top 'of the box.

box. The neck 6 contains an oil screen 7, as

usual, andvhas a removable closure cap 8 fitting'over its uppefrend, as shown in'lfigs. 1

and 5. The filler neck 6 may be located at either end of the reservoir, depending on the requirements Vof the design.k l A f y InF ig. 1, I have shown the reservoir 1 provided with Ya plurality of pump unitsso thatthe oil in the reservoir may be simultaneously and vautomatically,v pumped therefrom to anumber, of different places of lubrica- 3 and`11., Y y Y The cross-head l17 extends on opposite sidesl of the shaft 15in' a direction parallel Vto the tion, as bearings, cylinders, etc.v

The pump units are suspended from the top Aof the reservoir V1 andv arranged to extend across the same in side byside relan tion between the side walls 2, 2 of the reservoir, as shown in Figs. 2 and 4. The coverv plate 5 is providedA with a plurality of slots v 9 extending part way across'the same and disposed to receive the several pump units, as 'illustrated in Fig. 4'.

'The'fseveral pump units yare alike in construction and operation, so a description of one will suice for all. YEach pump unit has a laterally narrow elongated cast or forged body which passes through andA fits in itsV slot 9 in the cover plate 5 to close the slot, said body having aheight toextend aboveand below the cover plate. The body has' a'substantially flat surrounding flan e k10 between its upper and lower ends, said ange seating on the top surface of the cover plate 5 about the slot 9 to suspend or support the Vunit in place on the reservoir. The flange 101extends across the top of the cover plate 5 from oneside wall 2 of the reservoir to thel other and issecured thereto by screws 11', 11, as

shown in Figs.2 and 3. The reservoir; 1 has inwardly extending parts at its upper edges to receive these screws, the latter also passing through the portions of thecover plate 5 interposed between. the ends of theY flange cover plate on the reservoir.`

Horizontally disposed in the reservoirlbelow the' several pump units and common to all of them is a shaft 12, preferably hexagonalpin, cross-section, as shown in Fig.

Mounted on said shaft for rotation therewith area pluralityof cams or eccentrics 13, 13

one for each pumpunit and disposed directly belowy the same.A For each cam there is a yoke 14 lopen at` one end sothat it may readilyslip endwise on andA off the cam without removing either the cam or theshaft from the reservoir. i l s. Y

e The yoke 14 is vertically disposed and has y its upper and lower portions 'bearing against the upper and lower peripheries, respective-V ly, of the cam, so as to be positively raised and lowered in the rotation of the cam. A stroke shaft 15 is secured to and extends upward from the yoke 14 and passes through guide bosses 16, 16 provided 1inV the body of the ,Y

unit and extending above and below the flangeV 10 to provide a relatively long bearing on the body for the stroke shaftf15 and thus avoid the necessity and `.expense of making a bearing for this shaft either inthe cover plate 5 or on the bottom wall 4 of the reser- `Voir 'as heretofore. The upper end of this shaft "15 extends above the uppermost boss 16 and Vis releasably secured to ay horizontal cross-head 17 iby a suitable screw cap 18,-the

upperk end of the shaftbeingV reduced and v purpose,-as shownin Y threaded 'for the 17 and receive the vertically disposed plungers 19, 20 of the pumping elements offV the unit. The upperxportion of the plunger'-Y 19ofthe primary pump' extends 'above the cross-head andisthreaded along itslength to receive nuts 21, 22 on opposite sides of theV cross-head, V`17, so that thelatter may'reciprocate the plungerv19 inthe up and down movements ofthe stroke shaft '15. ,Y The upper nut 21 is adjustable on theplungerV 119 so as j to regulatethe amount of up and down movement imparted to the plunger 19by the stroke shaft 15. To hold 4the nut 21 in its positionf` of adjustment, I provide above thesame on f the plunger a jam nut 23. Thelowernut 22 is fixed on the plunger so as to provide Ya stop for the cross-head'-on'its downward stroke.V

The delivery plunger20 hasV positive con-'V nection with its end of the crossfliead 17 by being shouldered Vonk oppositesides of the 1 cross-head-so as to be operated at full strokes atall times regardless of the amount oflost motion providedffor the stroke ofthe plunger 19 in the adjustment ofl the.nut 21 on'the` latter. Y Thisptogether with the partial vacuum feature to be presently described, makes the plunger 2O deliver onf'each downwardorfpressure stroke the fullamount' of oil drawnV vfrom the lreservoir 1 on` eachV up lA orsuction strokecf the primary plunger V19. As shown inA FigQS, thegplungers 19,720

mfk

reciprocate inbosses 24,24 provided in" the f body `of the uniton the upperjside ofthe Y flange 10.l The bores of thesebossescontinuef downward into pump barrels 25,",f26'carried by the bodyV of the unit and yextending Vbelow Y' the flange 10'. The bores ofthe barrels 25, 26 are closed at their` lower en'ds and haveopenings just above the same into horizonf tally disposed conduits-727,128, oneforeach,

Fig. 3. nects van intake. screen Si forming its barrel and preferably formed egral therewith, as shown. The conduit 27 connects with a vertically arranged conduit 29 extending above and below the same, as shown in The lower end of the conduit 29 conwi-th the upper end of suc ion tube 30 which extends downward toward the bottom wall of the reservoir rit the erttreme lower end of this tube 30 is suction valve assembly embodying a housing having l lower portion. An inwardly open g gravity check ball 32 is insaid housing for the lower end of the suction tube, as shown Fig. 3. The

screen is located closely adjacent the bottom wal f of the reservoir so as Vto be always in the oil supply. By having the Valve .32 at the eXtreme louf'er or intake end of the suction tube SO. the amount of oil drawn into the tube on each up stroke of the primary plunger 19 will be checked in the tube on nas-sing the e'lower end of a sight feed g aboyethe body of the glass Sel, as shown lass seats on suitfr above the flange 10. `lass is closed by a cap d of the g which secured to the'upper en d1 of the nozzle by a screw. Asshown, saro scilew when tightened clamps the glass against Une Gasket a d inakesa leak proof chamber for U t l "l l "'i the oil pumped therethrough.. \"oee .d ig. 3.)

,v 1 Y There is a grarnv closing ball check 3o at tne upper end of the conduit to prevent a retiirn flow the nozzle in the operation of the device. 1

P n .Gn each unstroke or the 19 on is dra wn into the oarrel 25 of said plunger from h the conduits 30 ano.

p n l 9 29 and forced into the sight glass chamber e4 through the nozzle on each down stroke D' l v Y i l r of said plunger, the chechl valyesHBQ and 3.1i reversely op ng and closing in Vv.ne up anc. downmovements of the plunger.r f

r'he body of thev unit has an oil outlet 1 1 .36 which is connected with the barrel f2.6 of ne t 1 A shown in 3, 13., ano. il.

Conduit 53S opens at one end into the barrel Le adyacent the closed lower end thereof, while the oth end said conduit 28 opens into the lower end' of delivery chamber 88. weich is provided with a pair or sup closing check balls S9, Il() i the connection of this cha` 28. Conduit 3? opens into point high enough above 'end of the barrel so as not to be uncovered by the plunger 2O until the lat-ter reaches the end of the conduitr29 cem livery plunger by a conduit the closed lower limit of its upper stroke, as shown in Fig. 3.

By this arrangement, plunger 20 closes the adjacent end of conduit 37 to barrel 2G during the maj or portion of the up stroke of the plunger, thereby allowing the .same to create a partial vacuum below it in the barrel during this up stroke and eecting the closing of the check Vballs 39, 10.` As soon as the plunger 20 uncovers the conduit 37, the vacuum is released and the oil will be quickly sucked into the barrel Q6 from sight glass chamber 34 through passages and 37. This action is very rapid and all of the o-il delivered to the sight glass chamber 34 on each down stroke of the primary plunger 19 will be quickly discharged into the barrel 26 on each up stroke of the delivery plunger 20. Thus no oil remains in the sight glass to build up and flood i TEMOR? l l e 'set to feed one or more drops of oil or a fraction of a drop to the sight'glass and de;

liver exactly the lsame amounts from` the delivery chamber, thereby making theV lubricator accurate in that it will deliver to the places for lubrication the same amounts of oil as fed through the sight glass. This is an important feature of my invention because the engineer in setting the stroke of the pri# mary plunger 19 for one or more drops of oil or a fraction of a drop or a continuous stream per stroke of the primary plunger, as the oonditi ons may require, and, seeing such amounts of oil going through the sight glass chamber,

knows that such amounts of oil, no `more and no less, are being `delivered to the places of lubrication. ThisV makes the device accurate and eflcient in its operation and insures an automatic and constant proper lubrication o'f the parts fed by the device. The delivery chamber 38 leads to a discharge con` nection l1 to which is secured a suitable pipe fitting 4t2, p so thatthe lubrieator may be connected to the conduits of the oil line. l i

The pump unit may be readily andv easily removed from the reservoir 1 by taking out the screws 11, 11 from the ends of the flange 10 'and taking off the cap nut 18 from the upper endof the stroke shaft 15. The body of unger 19 adjustable, the lubricator may which may be straightor an elbow 14 open at one end, it may be removed from v the cam 13 by canting the yshaft 15 to an angle with its upper end at or near the upper edge of the reservoir at the side opposite the yoke, as indicated in dotted. lines in Fig.

j 11. When in this position, the yoke may be swung upward from the'cam through thev medium of the shaft and be taken out of the top of the reservoir 1 through the slot 9 in the cover, as shown in dotted lines in Fig. 11..

` This is also an important feature of my invention because it enables the pump unit and stroke shaft with its yoke to be readily and easily removed `from thereservoir without dismantling the shaft 12er taking off the cam or disturbing the operation of the other pump units'or their connection with the resv ervoir or theshaft'12, if theA device is of the.l multiple unit type. Eachpunit has. a stroke shaft 1,5, therebyavoiding the necessity of having a stroke shaft connected with the operating plungers of-two adjacent units, as heretofore. Thus each unit maybe removed Y from the reservoir for inspection or repair ori such other attention as it=may require, without putting out of operation the adjacent unit, as when a stroke shaft is con` nected with two adjacent units as heretofore.

To prevent thel yoke14 .from sliding or.

working sidewiseoif of its cam 13, I provide discs 43, 43 .on opposite sides ofthe cam and pinned thereto, as shown in Figs. 3 and 6.

These discs overlap the 'upper and lowerV vportions of the yoke on opposite sides thereof and revolve withthe cam. In removingY the yoke rfrom the cam, the yoke is withdrawn from between the discs, the latter remaining on the cam to provide a retaining Vchannel for the yoke on its replacement.v

The plungers 19, 20 are packed in their respective bosses 24, 24, as shown in Fig. 3. rThe plungers extend through the packings and the nuts 44, 44 used therewith. By reason of this construction, the oil will leak up past the packing nuts 44, 44under excess pressures such as produced when the oil lines on the delivery side of the device are clogged byrdirtor other foreign matter. Thus oil leakingup past the packing nuts Vwillgive visible indication of the clogging and allowl for its remedy. 1 This is another important feature of my invention, as in lubricators as before constructed oil leaks would be through the bottom ofthe unit and could not be seen to indicate a lfaulty feed.

Two ball checks 39, 40 are provided on the delivery side of the unit so that a partial vacuum will be crea-ted in the barrel'26 on the up stroke of the plunger 2O in case eitherv valve fails toY seat due todirt or yother foreign matter collectingbetween the valve and its seat. Should both'valves vfail to seat, the plunger 20 will fail to crea-teapartial vacuum in the barrel'and consequently no oil will flow to the barrel. vThe sight'glass 34 will then vfill, due to the operation of the plunger 19, vand indicate by thatvcondition Y that the valves need cleaning. i

l With' the shaft 12 hexagonal, the cams13` may be set on the shaft with the high andy low portions vof the several cams in different positions with respect to each other about the shaft and thus' allow'the several pump* unitsto be operated in alternation and avoid any excess pull on the operating'lever 45,

as would be the case should all the cams be set (See Fig. 15.) By j on the same position. being able to set'thefcams at different positions, the cams maybe disposed so as to 0perate the pumpsin'timed relation to the operation of the engine being attended by the lubricator. When soioperated, no ratchl et means would be employed with the shaft 12, thek latter at such time beingdirectly connected with thedesired moving part Vof the engine. i 1' The Ashaft V12 isfmounted inthe reservoir 1 abovethe bottom .Wall 4"thereof in thefol-Y lowing manner. f As shown in Figs. l, 6 and' 7, the stuiling boxes 46, 47 are inserted through the end walls 3, 3 of thereservoir in line with the shaft 12. Through each box. j

extends a cylindric shaft section 48, 49. These shafts extend into the reservoir land enter recesses in the adjacent ends ofthe shaft 12, which terminates short of the end walls o of the reservoir, as shown. Shaft 12` is secured to sha-ft 48 by a Cotter-or other pin 50. Loose on shaft'49 just inside of the res-V ervoir 1 is a ratchet wheel 57h/,Shaft 12 abuts against the'adjacent face of this Wheel in a recess made thereinand has'a pair of lugs or tongues 52, 52 (Figs. 7 and 9) to fit in radial slots 53, 53 made in the Wheel atV said .recess so that the wheel when turned will rotate shaft 12.' The wheel is turned through a spring controlled pawl 54 carried -K los by an arm 55 fixed to` shaft 49. A spring pressed dog 56 is mounted in the reservoir to engage the wheel 51 and prevent it from turning inthe wrong c lirection.-V TheA op-y erating lever isl secured tosha'ft 49 for turning the same. Y Y

`Loosely Vand slidably mounted on'the othern shaft/18 exterior of the reservoir is azhand lever 57, which has a seat to engage a'pin 58` on said shaft for 'clutching the hand leverl thereto Whenever it is desiredto operateVV the plunger rmanually toy accelerate Ythe' oil delivery ror vflush the parts being lubricated.

By having the shaft 12 short Vof `therfull length of the reservoir 1 and being mounted` therein in thefm'an'ner shown and describedp the shaft 12 maybe readily and veasilyfre-YV moved from the reservoir'by taking out the, pin and unscrewing the Ystuffing box 47,

from the reservoir. ThenV the .shaft 12 be withdrawn endwise throughthe opening;

in the end wall 3`of the reservoir, its cams" 13 sliding off the shaft,Vv as is apparent. This.

tion, because it provides for simplicity of construction and allows the device to be readily assembled and dismantled without the use of skilled labor.

When it is desired to-rotate the shaft 12 in timed relation to the engine being lubricated, the shaft 49 is connected with the moving part of the engine in such a manner that said shaft is rotated continuously in the direction permitted by the pawlA a. At this time the shafts 12 and Li9 are in effect directly connected through the pawl, etc.

It is to be observed that all of the' ball checks of the unit are located remote from the plungers 19, 2O so as not to follow the same in the. up strokes thereof and thus fail to seat the instant required for the efficient and accurate operation of the lubricator. Moreover, it is to be further noted that the plungers 19, and the stroke shaft 15 of each unit are all slidable in the body of the unit and in addition are aligned lengthwise of the body of the unit. This makes each unit'self coni tained with all of its parts within the margins of the flange 10. Consequently, the units, in a multiple unit lubricator, may be placed closer together than when a stroke shaft is provided for each two units and located between them as heretofore. Manifestly, more units can be assembled in a. reservoir of a given size than with the units as heretofore constructed. It will be noted in F ig. 4, that the slot in the cross-head 17 at the primary plunger 19 is longer than the slot at the opposite end of the head. rlhis is provided so that the cross-head may be slid endwise toward the primary plunger when releasing the other plunger or toward the latter plunger wncn engaging the same on either disconnecting or connecting the parts.

rlhe details of construction and arrangenient of parts shown and described may be variously changed and modified without departing from the spirit and scope of my invention.

l claim as my invention:

1. In a force feed lubricator, the combination with a reservoir, of a pump unit suspended therein and having pumping elements, stuffing boxes in two of the opposed walls of said reservoir, shaft sections journaled in said boxes and extending into said reservoir, a separate actuating shaft between and supported by the inner ends of said shaft sections, means whereby the actuating shaft may be turned by either of said shaft sections, a cani slidable on said actuating shaft but rotatable therewith, and means affording a. driving connection from the cam to said pumping elements, said actuating shaft being slidable through the opening aorded in the reservoir on removing one of said boxes so that said actua-ting shaft may be inserted in and removed from said reservoir.

2. In a force feedlubricator, the combina- A tion witha reservoir, of a pumpunit havingV a one-piece body extending acrossthe top of the reservoir and mounted on the adjacent upright marginal walls thereof for suspend-70 ing the unit in the reservoir, primary and delivery pump plungers and a stroke shaft all slidably mounted in the one-piece body and extending above the same with the plungers aligned with and onopposite sides of the 775 stroke shaft, said shaft also extending downward through the one-piece body with it-s lower end in the reservoir below the bod means releasably connecting theupper en s of the plungers to the ,upper end of the stroke 330 shaft whereby the shaft may operate said plungers and also may be disconnected therefrom to permit the removal of the one-piece body with its plungers from the reservoir without taking the shaft therewith, an actuating cam mounted in said reservoir below said body, and a driving connection between the lower end of the stroke shaft and the cam permitting-the shaft to be readily removed from and applied to the cam after the re- 1h90* moval of the on-e-piece body with its plungers from the reservoir without disturbing the mounting of the vcam in the reservoir.

3. In a force feed lubricator, the combination with a reservoir, of a pump unit having a 9-5 one-piece body extending across the top of the reservoir and mounted on the adjacent upright marginal walls thereoffor suspending the unit in the=reservoir, primary and delivery pump plungers and a stroke shaft all slidx00 ably mounted in the one-piece body and extending above the same with the plungers aligned with and on opposite sides of the stroke shaft, said shaft also extending downward through the one-piece body Awith the lower end of the shaft in the reservoir below the body, means releasably connecting the upper ends of the plungers with the upper end of the stroke shaft whereby the shaft may operate the plungers and also be disconnect- 7110 ed therefrom to permitl the removal of the one-piece body with its plungers from the reservoir without taking the shaft therewith, an actuating cam mounted in said reservoir below said body, and a 'driving yoke secured 115 to the lower end of said stroke shaft and en-V gaging said cam for operation thereby, said yoke having an opening through one end whereby the yoke may be readily slipped on and off the cam after the removal ofthe one- "120,

piece body andvits plungers from the reservoir without disturbing the mounting o-f the latter in the reservoir.

il. In a force feed lubricator, the combination with a reservoir, of a plurality of pump units suspended in the reservoir from the upper end thereof in side by side relation, each pump unit having a body with alignedV primary and delivery pump plungers and a stroke shaft all slidably mounted in the body 3,53

V- andextending above'the saine, withthe'stroke shaft Valso extending Vdov'vnward through-the Vbody and having its 'lower endin'the reserf Y voirbelowthe body,'inea'ns releasably con- .5 necting the upperendsof theiPlungers andV thestroke shaft of each unit together whereby the shaft may operate said plunge-rs and also be disconnected therefrom to Vpermit re- Ymoval of the body 'andits plungers from the Y r m .reservoir without taking the shaft therewith,

an actuating shaft mounted in said reservoir ybelow the bodies of the several units and,Y comwvirionv thereto,'cams on saidV actuating shaft 1 and having'driving .connections with the :.lo'wer ends of the stroke shafts of the respec- 4tive, units for reciprocating the'sarne, and means connecting the cams 4with'the actuating shaft in a'manner permittingy adjustmentof 'thecalns to Vdifferent Ypositions about said `20-shaftvfor operating the units in alternation.Y

V5.,V In a .force-.feed ylubricator, the combination with a' reservoir,V of 'a plurality of purnpunits suspended in the reservoir from 1 Vthe .upper end thereof inside bysiderelation, '25 each pump unit having a body with aligned primary v'and delivery pump plungers and a 'stroke shaft all slid ably mounted in the vbody and extending above the salne with the stroke shaft also extending downward through thev 30 body and having its lower end in the reservoir `below the body, `means releasably lconnecting the upper ends of the plungers and 'the' stroke shaft of each yunit together Ywherem Y, the shaft may operate said plungers and .'35 1 also be disconnected therefromV to permit removal of theA body and itslplungers from vthe reservoir without taking the shaft there- `with, an actuating shaft inountedin said reservoir below theibodies of the severalfunits i' '4 and common thereto, cams on said actuating shaft and having driving connectionswith, the lower ends of the stroke shafts ofthe respective units for reciprocatingthe sanne, f Y 'said actuating shaft being polygonal in' cross- '45 section so thatY the camsmaybe adjusted f about the shaft to differentpositions for actuating thel units vin alternation. In testimony whereof I afliX myr signaturey this 10 day of September, 1926. y l i Y Y @-450 Y i i j. :LOUIS w. DROTT. f Y 

